The png_check_keyword function in pngwutil.c in libpng before 1.0.42, and 1.2.x before 1.2.34, might allow context-dependent attackers to set the value of an arbitrary memory location to zero via vectors involving creation of crafted PNG files with keywords, related to an implicit cast of the '\0' character constant to a NULL pointer.

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Pardus Linux Security Advisory 2009-10 security@pardus.org.tr
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Date: 2009-01-23
Severity: 2
Type: Remote
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Summary
=======
The png_check_keyword function in pngwutil.c in libpng before 1.0.42,
and 1.2.x before 1.2.34, might allow context-dependent attackers to set
the value of an arbitrary memory location to zero via vectors involving
creation of crafted PNG files with keywords, related to an implicit cast
of the '\0' character constant to a NULL pointer.
Description
===========
NOTE: some sources incorrectly report this as a double free
vulnerability.
Affected packages:
Pardus 2008:
libpng, all before 1.2.34-17-7
Resolution
==========
There are update(s) for libpng. You can update them via Package Manager
or with a single command from console:
pisi up libpng
References
==========
* http://bugs.pardus.org.tr/show_bug.cgi?id=9052
* http://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-2008-5907
* http://openwall.com/lists/oss-security/2009/01/09/1